The modular square shelter is designed to be a fallout shelter that feels as close to home as possible. It is not as strong as a round shelter and does not have the massive amount of under floor storage as a round shelter, but it can be built out to look just like a normal home on the interior. The modular shelters are made out of 1/4″ steel walls that are 8 feet tall. The exterior structural supports vary from structural channel to structural I-beam to rectangular tubing.